type Student = {
	name: string
	// gender: string // 需求：只能取 男，女
	gender: '男' | '女' // 需求：只能取 男，女
	score: number
	height: number
	study: () => void
	play?: () => void
}

let stu1: Student = {
	name: '小花',
	gender: '女',
	score: 100,
	height: 160,
	study: () => {}
}

let stu2: Student = {
	name: '小白',
	gender: '男',
	score: 100,
	height: 170,
	study: () => {}
}
